Descarbonylethoxyloratadine, also called desloratadine, is chemically known as 8-chloro-6,11-dihydro-11-(4-piperidylidene)-5H-benzo[5,6]-cyclohepta[1,2-b]pyridine. Desloratadine, a metabolic derivative of loratadine, is a long-acting tricyclic histamine antagonist with selective H1-receptor histamine antagonist activity. Descarbonylethoxyloratadine is indicated for the relief of the nasal and non-nasal symptoms of allergic rhinitis (seasonal and perennial) in patients 12 years of age and older. It is also indicated for the symptomatic relief of pruritus, reduction in the number of hives, and size of hives, in patients with chronic idiopathic urticaria, 12 years of age and older.
U.S. Pat. No. 6,100,274 claims a stable pharmaceutical composition of desloratadine comprising a desloratadine-protective amount of a pharmaceutically acceptable basic salt and at least one pharmaceutically acceptable disintegrant. The patent mentions that acidic excipients discolor and decompose desloratadine. Desloratadine compositions were found to discolor when stored at 75% relative humidity (“RH”) and a temperature of 40° C., alone or in combination with various excipients. This color instability in the active ingredient was attributed to a very minute amount of degradation product, the N-formyl impurity of desloratidine, which is formed due to the presence of a wide variety of excipients commonly used in oral formulations—especially tablet formulations. The unsuitable excipients include acidic excipients including, but not limited to, stearic acid, povidone and crospovidone, and other acidic excipients having a pH of less than 7 in water, preferably in the range of about 3 to 5, as well as excipients such as lactose, lactose monohydrate, sodium benzoate, and the like. The patent teaches the use of calcium, magnesium and aluminum salts of carbonates, phosphates, silicates and sulfates, or mixtures thereof as stabilizers. However, the patent does not teach any other means of stabilizing desloratadine.
United States Patent Application Number 20020123504A1 relates to stable pharmaceutical compositions of desloratadine formulated to avoid the incompatibility between desloratadine and reactive excipients such as lactose and other mono- and di-saccharides. Disclosed compositions include lactose-free, non-hygroscopic and anhydrous stable pharmaceutical compositions of desloratadine. The patent application teaches that stable composition of desloratadine can be obtained by using anhydrous process and excipients, such that the unbound water that may be present in the formulation is insufficient to initiate and/or accelerate any reaction of desloratadine with reactive excipients. Other means of stabilization taught by the patent application include coating of desloratadine particles to avoid contact with reactive excipients, or using large particles of desloratadine, so that surface area of contact with the reactive excipients is reduced. However, the methods suggested in this application either provide solutions that involve avoiding conventional formulation procedures such as wet granulation, or suggest other means that may affect bioavailability of the formulation, for example, coating or using large particles.